Since the rotary drilling system has been in use it has been commonplace to use a first elevator as a temporary substitute for a spider to support a tubular well string while a second elevator, supported by the bails of the traveling block, engages the lower shoulder of the top connector of a tubular joint being added to the string. When the last added pipe section is safely secured to the string, the top elevator then lifts the string to allow the first elevator to be slid aside. The string is then lowered by the second elevator until it engages the rig floor level support which is usually a landing table or rotary table cover plate. The traveling block bails are then removed from the second elevator and attached to the first elevator, by which a new pipe section is accessed, and the process is repeated. This is referred to as "circulating the elevators". The procedure is reversed to remove a tubular string from the well.
Several different pipe handling procedures have been developed to alter the handling procedure defined above but no single best way has evolved.
The process described above has naturally evolved to satisfy the need to handle risers approaching a platform from the sea bed below. Risers can usually afford connectors of larger outside diameter, compared with well string tubing, and there is usually enough surface to accept the loads, and contact areas, of both elevator and support table if the load transmitting elements are arranged for that purpose.
In some cases, the pipe string outer surfaces are very sensitive to surface damage. That sensitivity usually results from metal, surface, and heat treatment selection to best accept local chemical conditions. Each type of connection, however, can be supplied with a sleeve with mating surfaces that minimize localized stresses when lifting the string by surfaces the sleeve makes available.
It is desirable and an object of this invention to provide apparatus and methods to avoid the repeated disconnecting of the bails to circulate the elevators.
It is another object to simplify the nature, use, and cost of structure to serve the simple support function of the spider, and allow the novel support table and elevator to simultaneously engage the lifting areas of the string components.
It is still another object of the invention to provide a temporary sleeve to safely engage complex surfaces of the pipe and connector and to provide more usable surface, or surfaces, to engage the support table and elevator simultaneously to change support for the string to and from the elevator.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.